Recently, broadcasting services have been generally provided in the form of video communication services integrated with communication services. The video communication services are based on a broadband network that provides high-speed information delivery on a multimedia device capable of fast information processing.
The multimedia device supporting the video communication service consumes a lot of power due to image processing. In particular, a resolution of an image to be processed may be a main factor that determines a power consumption of the multimedia device in a display operation. For example, in a portable multimedia device (hereinafter, referred to as a ‘portable terminal’), a power consumption during a display operation may increase in proportion to a resolution of an image to be processed.
An increase in the resolution of the image may cause an increase in a bandwidth on a link in which information about the image to be processed is to be delivered. For example, a bandwidth consumed by one multimedia device to deliver multimedia data to a cloud server may increase in proportion to a type, a resolution, or the like of target multimedia. In another example, when one multimedia device delivers multimedia data to another multimedia device over a network, a bandwidth to be used may increase in proportion to a type, a resolution, or the like that determines a size of the multimedia data to be delivered.
For these reasons, most multimedia devices use various encoding and decoding techniques to reduce the amount of information of multimedia data. The encoding and decoding techniques allow efficient use of a capacity of a recording medium such as a memory and a bandwidth of a transmission medium.
Codecs that support encoding and decoding of the multimedia data have been developed for types of multimedia to improve encoding efficiency. For example, codecs for still images may include joint photographic experts group (JPEG), JPEG 2000, lossless JPEG, portable network graphics (PNG), picture motion browse (PMB), and so forth, and codecs for moving images may include motion JPEG, moving picture experts group (MPEG)-1, MPEG-2, MPEG-4, H.263, H.264, high efficiency video coding (HEVC), and so forth. Codecs for audio may include MPEG-1 layer I, MPEG-1 layer II, MPEG-1 layer III, advanced audio coding (AAC), high-efficiency (HE)-AAC, free lossless audio codec (FLAC), and so forth. Codecs for voice may include G.711, G.718, adaptive multi-rate (AMR), AMR-wideband (WB), and so forth.
The multimedia device may use different codecs by taking encoding efficiency into account, even for the same type of media. For example, a first multimedia device may use JPEG as a codec for still images, and a second multimedia device may use PNG as a codec for still images.
As another issue, the multimedia device needs to have a protection scheme for produced and consumed multimedia data. For example, the multimedia device has to be capable of encrypting produced multimedia data or decrypting encrypted multimedia data for consumption.
Generally, in the multimedia device, encoding and decoding and encryption and decryption may not be easily compatible with each other. To maintain codec compatibility, encryption and decryption have to be processed at a level prior to encryption, that is, a value level. For example, when encoded multimedia data is encrypted, the multimedia device entropy-decodes the encoded multimedia data, encrypts the entropy-decoded multimedia data, and then entropy-encodes the encrypted multimedia data. On the other hand, when encrypted multimedia data is decoded, the multimedia device entropy-decodes the encrypted multimedia data, decrypts the entropy-decoded multimedia data, and then entropy-encodes the decrypted multimedia data.
When the multimedia data is a still image or a moving image, the multimedia device may provide a low-resolution image. The low-resolution image may be a thumbnail image. The multimedia device may use a thumbnail image to identify the multimedia data.
The low-resolution image may be generated by a personal computer (PC), a smartphone, a cloud server, or the like by using still image or moving image information based on a corresponding policy. Thus, when the multimedia data is encrypted, the low-resolution image may also be encrypted. In this case, the identification of the low-resolution image by another multimedia device may be restricted.
To address this problem, a complicated procedure needs to be performed. For example, an encrypted image has to be decrypted and a low-resolution image has to be generated from the decrypted image. However, even for the low-resolution image generated in this way, a scheme for forming an organic relationship with the encrypted original image is required.
The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present disclosure.